This is what makes time travel possible...is that a flux capasitor
http://img.photobucket.com/albums/v728/mrmcnuggett/orangeback.jpg

what is all that?
capacitor

In interesting fact, a capacitor is two conductors with non-conducting material (or vacuum) between. Usually "plates' of metal. But can be wires in proximity, too.
The effect is to retain an electrostatic charge. Leyden invented the capacitor centuries ago. The Leyden jar... googleable.

Flux is magnetic lines of force. Electro-magnetic.
Caps or a rubbed comb? Electro-static. No lines of force; only electromotive potential.

Now WTH is in that Lava? FORCE for sure, but whaaaa? is it?

I could guess pretty accurately that it's a bass reflex speaker.
This sort of woofer can give a lot more true bass, less thumpy maybe, than the typical tuned small sealed box woofer. But oww, it will have a resonance peak for sure! Whoomph. It needs to really have the whole car interior.

If a woofer were mounted to the bottom of the floor pan, firing either up or down, with the floor pan as the "baffle", then the bass effect inside the car would be treeeeemendous, without much need for massive watts to drive. Windows up? Infinite baffle, sealed box effect. Windows cracked in various degrees? Ported bass reflex (more bass, with a tunable peak, probably quite low in F.)

big blind spot!!!

boy if you travel back in time in the xb, i wonder what kind of impact would you cause to the cars design today.